A female electric eel on display at the New England Aquarium, Boston Massachusetts.
Native to the Amazon basin, the electric eel is not a true eel, but a type of true fish.
Using a series of bio-sensing organs all along it's body, this apex predator can generate electric shocks of up to 600 volts for hunting and self-defense.
In spite of a fearsome reputation, the electric eel can be quite gentle. Biologists have been reported swimming unaided with the animal in the wild. As long as they were careful not to disturb the animal, they could swim within feet of it and not feel so much as a shock.